Publications by authors named "Sean Morrison"

We examined the associations between physical activity (PA)-measured through self-reported walking and vigorous activities-and pain occurrence (self-reported bothersome pain or frequent pain medication use), and persistent pain (pain occurring for two consecutive years). This analysis used a large, nationally representative sample of 2279 older adults from the National Health and Aging Trends Study of 2015-2018, and applied generalized estimating equation regression with propensity score weighting. Approximately 70% and 50% of the participants reported walking and vigorous activities respectively at baseline.

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Peripheral nerves promote mouse bone marrow regeneration by activating b2 and b3 adrenergic receptor signaling, raising the possibility that non-selective b blockers could inhibit engraftment after hematopoietic cell transplants (HCTs). We observed no effect of b blockers on steady-state mouse hematopoiesis. However, mice treated with a non-selective b blocker (carvedilol), but not a b1-selective inhibitor (metoprolol), exhibited impaired hematopoietic regeneration after syngeneic or allogeneic HCTs.

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Fatty acid oxidation is of uncertain importance in most stem cells. We show by C-palmitate tracing and metabolomic analysis that hematopoietic stem/progenitor cells (HSPCs) engage in long-chain fatty acid oxidation that depends upon carnitine palmitoyltransferase 1a (CPT1a) and hydroxyacyl-CoA dehydrogenase (HADHA) enzymes. CPT1a or HADHA deficiency had little or no effect on HSPCs or hematopoiesis in young adult mice.

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Evolutionarily conserved selenoprotein O (SELENOO) catalyzes a post-translational protein modification known as AMPylation that is essential for the oxidative stress response in bacteria and yeast. Given that oxidative stress experienced in the blood limits survival of metastasizing melanoma cells, SELENOO might be able to impact metastatic potential. However, further work is needed to elucidate the substrates and functional relevance of the mammalian homologue of SELENOO.

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Mitochondrial DNA (mtDNA) mutations are frequent in cancer, yet their precise role in cancer progression remains debated. To functionally evaluate the impact of mtDNA variants on tumor growth and metastasis, we developed an enhanced cytoplasmic hybrid (cybrid) generation protocol and established isogenic human melanoma cybrid lines with wild-type mtDNA or pathogenic mtDNA mutations with partial or complete loss of mitochondrial oxidative function. Cybrids with homoplasmic levels of pathogenic mtDNA reliably established tumors despite dysfunctional oxidative phosphorylation.

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Context: While specialist palliative care is associated with improved end-of-life quality metrics for patients with advanced cancer, its effectiveness may differ between hospitals.

Objectives: To examine variation in palliative care program performance on end-of-life care quality metrics.

Methods: Retrospective cohort study of palliative care programs that participated in the National Palliative Care Registry, 2018-2019.

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Hematopoietic stem cells (HSCs) and erythropoiesis are activated during pregnancy and after bleeding by the derepression of retrotransposons, including endogenous retroviruses and long interspersed nuclear elements. Retrotransposon transcription activates the innate immune sensors cyclic guanosine 3',5'-monophosphate-adenosine 5'-monophosphate synthase (cGAS) and stimulator of interferon (IFN) genes (STING), which induce IFN and IFN-regulated genes in HSCs, increasing HSC division and erythropoiesis. Inhibition of reverse transcriptase or deficiency for cGAS or STING had little or no effect on hematopoiesis in nonpregnant mice but depleted HSCs and erythroid progenitors in pregnant mice, reducing red blood cell counts.

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Article Synopsis
  • Ascorbate (vitamin C) decreases the function of hematopoietic stem cells (HSCs) and helps prevent leukemia by enhancing the activity of the Tet2 tumor suppressor.
  • Deleting the Slc23a2 transporter from hematopoietic cells caused a significant drop in ascorbate levels within HSCs and multipotent progenitors (MPPs) but did not affect overall plasma ascorbate levels.
  • This deficiency led to increased reconstitution and self-renewal capabilities of HSCs and MPPs when transplanted into irradiated mice, particularly in their quiescent states, indicating that low ascorbate levels may enhance their long-term potential.
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Article Synopsis
  • The study investigates how cellular metabolism changes during hematopoiesis, focusing on the effects of mitochondrial adenylate kinase 2 (AK2) deficiency in a severe immunodeficiency syndrome called reticular dysgenesis.
  • Using patient samples and CRISPR-modified human hematopoietic stem cells, the research reveals that AK2 deficiency affects mTOR signaling differently in early versus late granulocyte development, demonstrating the importance of metabolic checkpoints.
  • While early-stage AK2-deficient cells maintain survival due to effective metabolic regulation, late-stage cells experience unchecked mTOR activity and energy depletion, leading to proliferation arrest and cell death.
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Importance: The widowhood effect, in which mortality increases and function decreases in the period following spousal death, may be heightened in older adults with functional impairment and serious illnesses, such as cancer, dementia, or organ failure, who are highly reliant on others, particularly spouses, for support. Yet there are limited data on widowhood among people with these conditions.

Objective: To determine the association of widowhood with function and mortality among older adults with dementia, cancer, or organ failure.

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Valproic acid (VPA) is an effective and widely used anti-seizure medication but is teratogenic when used during pregnancy, affecting brain and spinal cord development for reasons that remain largely unclear. Here we designed a genetic recombinase-based SOX10 reporter system in human pluripotent stem cells that enables tracking and lineage tracing of Neural Crest cells (NCCs) in a human organoid model of the developing neural tube. We found that VPA induces extensive cellular senescence and promotes mesenchymal differentiation of human NCCs.

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Why individuals with Down syndrome (DS) are more susceptible to SARS-CoV-2-induced neuropathology remains elusive. Choroid plexus (ChP) plays critical roles in barrier function and immune response modulation and expresses the ACE2 receptor and the chromosome 21-encoded TMPRSS2 protease, suggesting its substantial role in establishing SARS-CoV-2 infection in the brain. To explore this, we established brain organoids from DS and isogenic euploid iPSC that consist of a core of functional cortical neurons surrounded by a functional ChP-like epithelium (ChPCOs).

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Purine nucleotides are vital for RNA and DNA synthesis, signaling, metabolism, and energy homeostasis. To synthesize purines, cells use two principal routes: the de novo and salvage pathways. Traditionally, it is believed that proliferating cells predominantly rely on de novo synthesis, whereas differentiated tissues favor the salvage pathway.

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Background: In response to a growing need for accessible, efficient, and effective palliative care services, we designed, implemented, and evaluated a novel palliative care at home (PC@H) model for people with serious illness that is centered around a community health worker, a registered nurse, and a social worker, with an advanced practice nurse and a physician for support. Our objectives were to measure the impact of receipt of PC@H on patient symptoms, quality of life, and healthcare utilization and costs.

Methods: We enrolled 136 patients with serious illness in this parallel, randomized controlled trial.

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Cell segmentation is the fundamental task. Only by segmenting, can we define the quantitative spatial unit for collecting measurements to draw biological conclusions. Deep learning has revolutionized 2D cell segmentation, enabling generalized solutions across cell types and imaging modalities.

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Autophagy is central to the benefits of longevity signaling programs and to hematopoietic stem cell (HSC) response to nutrient stress. With age, a subset of HSCs increases autophagy flux and preserves regenerative capacity, but the signals triggering autophagy and maintaining the functionality of autophagy-activated old HSCs (oHSCs) remain unknown. Here, we demonstrate that autophagy is an adaptive cytoprotective response to chronic inflammation in the aging murine bone marrow (BM) niche.

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Article Synopsis
  • - The study investigates the use of hospice aide care in various residential settings (community, assisted living, nursing homes) among Medicare beneficiaries who died between 2010 and 2019.
  • - Findings reveal that hospice aide visits were least frequent in community settings (64.4%) compared to assisted living (76.6%) and nursing homes (72.6%).
  • - Although hospice aides provide essential care, the reasons for their use did not significantly differ by setting, indicating a need for better understanding of how to optimize hospice care across different types of residences.
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Ascorbate (vitamin C) limits hematopoietic stem cell (HSC) function and suppresses leukemia development by promoting the function of the Tet2 tumor suppressor. In humans, ascorbate is obtained from the diet while in mice it is synthesized in the liver. In this study, we show that deletion of the Slc23a2 ascorbate transporter severely depleted ascorbate from hematopoietic cells.

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Congruence between the preferred and actual place of death is recognised as an important quality indicator in end-of-life care. However, there may be complexities about preferences that are ignored in summary congruence measures. This article examined factors associated with preferred place of death, actual place of death, and congruence for a sample of patients who had received specialist palliative care in the last three months of life in Ireland.

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Context: For patients with advanced cancer, high intensity treatment at the end of life is measured as a reflection of the quality of care. Use of specialist palliative care has been promoted to improve care quality, but whether its use is associated with decreased treatment intensity on a population-level is unknown.

Objectives: To determine whether receipt of specialist palliative care use is associated with differences in end-of-life quality metrics in patients with metastatic cancer.

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The bone marrow contains peripheral nerves that promote haematopoietic regeneration after irradiation or chemotherapy (myeloablation), but little is known about how this is regulated. Here we found that nerve growth factor (NGF) produced by leptin receptor-expressing (LepR) stromal cells is required to maintain nerve fibres in adult bone marrow. In nerveless bone marrow, steady-state haematopoiesis was normal but haematopoietic and vascular regeneration were impaired after myeloablation.

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In response to the scarcity of advanced in vitro models dedicated to human CNS white matter research, we present a protocol to generate neuroectoderm-derived embedding-free human brain organoids enriched with oligodendrocytes. We describe steps for neuroectoderm differentiation, development of neural spheroids, and their transferal to Matrigel. We then detail procedures for the development, maturation, and application of oligodendrocyte-enriched brain organoids.

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We assessed the spatiotemporal patterns of hospitalization with comorbid cancer and dementia. Using the 2013-2018 inpatient claims data for Medicare fee-for-service (FFS) beneficiaries, we calculated hospitalization rates by dividing the total admissions from individuals with the co-presence of a major cancer (breast, prostate, lung, and colorectal) and dementia diagnoses with the total counts of FFS beneficiaries aged 65 or older. We identified 22 hotspots with high hospitalization rates that showed heterogeneous spatial and temporal utilization patterns.

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